Jormalainen, V., Merilaita, S. & Tuomi, J. 1993: Male choice and male-male competition in Idotea baitica (Crustacea, Isopoda). Ethology 96, 46–57.
Male Choice and Male-male Competition in Idotea baitica (Crustacea, Isopoda)
Article first published online: 26 APR 2010
1994 Blackwell Verlag GmbH
Volume 96, Issue 1, pages 46–57, January-December 1994
How to Cite
Jormalainen, V., Merilaita, S. and Tuomi, J. (1994), Male Choice and Male-male Competition in Idotea baitica (Crustacea, Isopoda). Ethology, 96: 46–57. doi: 10.1111/j.1439-0310.1994.tb00880.x
- Issue published online: 26 APR 2010
- Article first published online: 26 APR 2010
- Received: August 12, 1993; Accepted: October 4, 1993 (W. Wickler)
Sexual selection in mate-guarding Crustacea may involve several processes: male choice, male-male competition, and female choice. To evaluate the relative importance of the different processes in mate choice of the aquatic isopod I. baitica we studied 1) the mate-choice criteria of males, 2) effects of sex ratio on the outcome of the mating contest, and 3) the role of size in male-male interactions. When given a choice between a small and a large female, males most often chose the one that matured earlier for parturial ecdysis. Maturity was a more important choice criterion than female size, but these also correlated positively. Large males had a mating advantage in both male- and female-biased sex ratios; pairing was size-assortative only in the male-biased ratio where guarding was also longer. If an extra male was placed with a precopulatory pair, 30 % take-overs occurred, large males surpassing. Present and earlier work suggests that male size is an asset in both intra- and intersexual interactions. There is little or no direct phenotypic sexual selection on female size: sexual selection for large males presumably contributes to the evolution of sexual size dimorphism in I. baitica.